A087306 a(n) is the start of the first arithmetic progression with common difference n of n numbers with the same prime signature.

1, 3, 155, 111, 3875983, 1333, 763274553951, 11978

Offset: 1

Author

Amarnath Murthy, Sep 02 2003

Keywords

• nonn
• hard

Comments

First column of A087307; main diagonal of A114656.

a(7) > 29*10^9; a(8) = 11978.

a(n) > 10^10 for n from 9 to 11. a(12) = 120998. [From Donovan Johnson, Oct 24 2009]

Examples

			a(4) = 111 as 111, 115, 119 and 123 all are of the prime signature p*q.
		

Crossrefs

Cf. A087307, A114656.

Extensions

Edited and extended by David Wasserman, Jan 08 2006

a(7) from Donovan Johnson, Oct 24 2009